IODP

doi:10.2204/iodp.pr.319.2009

Operations

Shingu, Japan port call

Loading for Expedition 319 began on 8 May 2009 at Shingu, Japan, a few days later than the originally planned sailing date because of bad weather in the area. A "prespud" meeting was held aboard the Chikyu on 9 May 2009. The Chikyu departed Shingu at 0930 h on 10 May 2009 to Site C0009 (proposed Site NT2-11B). The Expedition 319 operations summary is shown in Table T2.

Transit to Site C0009

The Chikyu departed Shingu for Site C0009 at 0930 h on 10 May 2009. Upon arrival at the site, the ship was set in dynamic positioning mode, the Big Head transducers were lowered, and a detailed seabed survey began at 1700 h on 12 May, finishing on 15 May. Official water depth at the site is 2082.3 m DRF (2054 m mud depth below sea level [MSL]). Two arrays of 10 transponders were deployed on 16 and 17 May and were immediately calibrated. The 36 inch conductor pipe, gamma ray attenuation (GRA)/Mudmat, and DAT were rigged up and the vessel moved 5 nmi upstream to lower the 36 inch conductor through the GRA and Mudmat on 17 May.

Hole C0009A

Initial operations began with a run in the hole and jet-in after the ROV seafloor survey.

Spudding in Hole C0009A (33°27.4704′N, 136°32.1489′E) took place at 0930 h on 19 May, followed by jetting-in the 36 inch conductor. The 36 inch conductor was successfully installed to 2136.8 m DRF (54.5 m DSF) by 1730 h on 19 May. However, the top connection of the 36 inch DAT sheared because of excessive slackoff and bending of the pipe above the DAT. A successful fishing run was completed on 23 May and the 26 inch drilling BHA reentered the 36 inch wellhead at 0700 h on 24 May. Drilling with the 26 inch BHA and MWD continued to 2795 m DRF (712.7 m DSF) and successfully reached the target depth on 25 May. A DPS malfunction occurred on 26 May, the investigation of which continued until 30 May, when the DPS was fixed and carefully observed in order to evaluate repairs, while 20 inch casing was prepared for installation. A final decision regarding the DPS failure was made on 31 May and planned operations resumed.

Preparations for running the 20 inch casing began on 1 June and the casing was installed to 2786.2 m DRF (703.9 m DSF) on 2 June with cement operations concluding on 3 June. Rigup for running riser pipe and BOP installation continued until 7 June. Meanwhile, a thruster failure occurred on 4 June and investigations into the cause continued until 8 June. Running down the BOP with riser pipe began on 8 June, with fairings being attached to the uppermost 11 sections of the riser pipe. Problems with the riser tensioner Riser Anitrecoil System (RARS) valves were discovered on 13 June and troubleshooting continued until 17 June. The rotating telescopic joint load ring became stuck on 19 June; however, the BOP was successfully connected to the wellhead on 21 June.

Following the BOP pressure test, the 17 inch drill out cement assembly was run into the hole on 24 June and drilled out 3 m of cement to 2798 m DRF (715.7 m DSF) by 25 June. After this, two LOTs were conducted at the casing shoe on 26 June (see "Leak-off test" below). Following the LOTs, the hole was drilled with a 12¼ inch drill BHA with MWD tools, including Power-V and MWD, beginning on 28 June. Cuttings and drilling mud gas were continuously collected during drilling. Including several short trips and circulation from bottoms up, 12¼ inch drilling reached TD at 3592 m DRF (1509.7 m DSF) on 2 July. The first two cores had very poor recovery because of equipment problems and other issues. Cuttings and drilling mud gas were collected during this phase. After coring, the RCB cored section was reamed with the 12¼ inch drilling assembly to open the hole and collect additional cuttings. Opening the hole with the 12¼ inch drilling assembly continued to a final TD of 3686 m DRF (1603.7 m DSF). During this time, lost circulation material was added to drilling mud to address lost circulation in the hole. On 12 July, two wireline logging runs were conducted: the first run with Environmental Measurement Sonde (EMS)-HRLA-PEX-GR, the second one with electromagnetic interference (EMI)-Hostile Natural Gamma Ray Spectrometry Cartridge (HNGC)-Sonic Scanner-EMS-Power Positioning Device and Caliper Tool (PPC). Prior to the third wireline logging run with the MDT, a 12¼ inch wiper trip assembly was run to clean the hole. After the wiper trip, MDT logging was conducted on 14 and 15 July.

Soon after MDT operations finished and the tools were pulled out of the hole, the hole was opened to 17 inches on 16 July. Drilling mud gas was collected during this hole opening phase. Hole-opening operations continued until the hole was reamed to 3650 m DRF (1567.7 m DSF) on 19 July. Several wiper trips and circulation bottoms ups were conducted to clean the hole prior to installing 13 inch casing. Preparations for running began on 21 July and the casing was successfully installed into the hole on 22 July. The 13 inch casing shoe was set at 3624.3 m DRF (1542 m DSF). Cementing the 13 inch casing took place on 23 July. During cementing operations, landing of the second cement plug could not be confirmed, and cement loss was observed (84% efficiency for the cement job). Upon pulling the cementing assembly to the surface, cement was found on the ports of the tool, indicating the possibility of a cement leak from the tool at the casing hanger. A junk basket with a 12 inch gauge ring was run into the hole to determine if any cement was left inside the 13 inch casing. The junk basket run encountered resistance at 2075–2080 m DRF (near the wellhead). After several attempts, the junk basket was rerun with an 8¼ inch gauge ring, and the casing was found to be sufficiently clear to run the VSI tool string. This plan modification, of running the junk basket rather than the scraper, as well as the cancellation of the CBL, was made in part to adjust the VSP operation time to match the availability of the shooting vessel, Kairei. Five VSI sensor arrays were rigged up on 24 July, and a check shot test was performed. There was a problem found in the VSP cables, so the sensor arrays were retrieved and checked. Four arrays of VSP tools (a total of 16 shuttles) were put back into the hole after finding a communication problem between Number 4 and Number 5 arrays. The walkaway VSP experiment with Kairei was started at ~2000 h on 24 July. One line and one circle shooting transect for the walkaway VSP experiment was finished on 25 July, followed by a zero-offset VSP on the same day (see "VSP operations"). Preparations to retrieve the BOP started on 26 July, and all riser pipes and the BOP were safely retrieved on 30 July. Retrieving transponders via ROV was completed early on 31 July, and the ROV set the corrosion cap into the wellhead on the same day. All operations for Hole C0009A were completed at 2400 h on 31 July. The Chikyu started moving to Site C0010 (proposed Site NT2-01J) at 0000 h on 1 August.

Leak-off test

After 20 inch casing was run to 703.9 m DSF and cemented to 708.6 m DSF, the hole was deepened to 715.7 m DSF. The hole was circulated and cleaned. Preparations for the LOT started at 2315 h on 25 June. From ~0000 to 0200 h on 26 June, there were various problems with a valve (the upper inline blowout preventer [IBOP]): the lower IBOP kill line was flushed and tested at 1000 pounds per square inch (psi).

The first LOT began at 0215 h, with 1.08 g/cm3 of KNPP mud at a pump rate of 0.25 bbl/m. Pumping stopped when the pump pressure reached 116 psi. The total volume pumped was 2.2 bbl. The leak-off pressure was 105 psi, or an equivalent mud weight (EMW) of 1.106 g/cm3 at the casing shoe. The maximum pressure was recorded as 116 psi (EMW = 1.109 g/cm3). After pumping stopped there was a flowback volume of 0.5 bbl.

Preparation for the second LOT started at 0306 h. Both mud tanks were filled for a line pressure test. Pressure was held at 272 psi. At 0322 h, the LOT proceeded with a 1.08 g/cm3 KNPP mud at a pump rate of 0.25 bbl/m. The pump was stopped when pressure reached 135 psi, for a total pumped volume of 3.6 bbl. The leak-off pressure was 105 psi, or an equivalent mud weight of 1.106 g/cm3. The maximum pump pressure was 133 psi, or an EMW = 1.113 g/cm3. After pumping stopped there was a flowback volume of 0.5 bbl.

VSP operations

The VSP experiment was divided into two parts: a walkaway VSP in conjunction with the research vessel Kairei and a zero-offset VSP conducted by the Chikyu alone. Operations for the walkaway VSP were adjusted from the precruise plans because of scheduling uncertainties and delays with expedition operations. One line of air gun shooting, combined with one circuit around Chikyu, was achievable in the time available. Before OBS deployment, synchronization of radio signals between the Kairei and the Chikyu was checked and confirmed. The Kairei began operations by dropping eight OBSs, in conjunction with four broadband OBSs, which had been placed in 2008. After pulling out of the hole following the junk basket run, the VSI tool string, consisting of 20 seismometers, was lowered into the hole to 2085.5 m DRF at 0730 h on 24 July. Caliper checks on each seismometer, used to couple the tools to the formation, thereby improving data collection, indicated that a short circuit had occurred somewhere along the string. Therefore, the VSI string was pulled from the hole at 1030 h and the 4 seismometers were removed to reduce risks of further cable problems, leaving 16 seismometers remaining on the VSI tool for the walkaway VSP. The VSI tool was again lowered into the hole at 1600 h and locked in the casing from 2999.2 to 3227.8 m DRF. Kairei deployed four air gun strings, and after a check shot at 1951 h, it was determined that the formation coupling was poor at this interval, so the VSI tool was raised to 2963.7–3222.3 m DRF and anchored in preparation for a shaker test, which tests the connection of the seismometers to the casing and, in turn, the casing to the formation. Kairei began moving along the linear transect, shooting at 2018 h, and recorded the first position at ~24.1 km, with a 60 m shot interval. When the Kairei reached a point 1 nmi from the Chikyu on 25 July at 0311 h, she made a slight deviation from course and then at 0327 h, an intermission in shooting until the circle (clockwise around the Chikyu) transect began at 0405 h. The shooting interval for the circle transect was 30 s at a distance from the Chikyu of 3.5 km; shooting finished at 0632 h. The Kairei then returned to the line transect and resumed shooting the linear transect at 0713 h. At 10.7 km from Hole C0010A, the Number 3 gun array on Kairei unexpectedly stopped firing; however, firing continued with the remaining 3 arrays. The line transect ended at 0847 h on 25 July, when the Kairei reached a point 29.3 km from Hole C0009A.

Preparations for the zero-offset VSP experiment began immediately; the Chikyu deployed a set of air guns suspended from a crane off the port side of the ship. These were shifted to a point farther from the Chikyu to avoid causing any damage to the azimuth thrusters from the underwater shocks. A delay of ~4 h occurred because of repeated failures of the shear pin on the compensation line. An additional delay was caused by the use of faulty shackles on the air gun assembly—the crane operator noticed that condemned shackles had been used and called for their replacement before deploying the air gun at 1145 h. The zero-offset VSP began with the VSI array in the same position it was for the walkaway VSP, but between shootings the array was moved upward in the casing at 122 m intervals. Shooting and recording began at 1620 h, and it was soon discovered that Seismometers 9 and 10 were malfunctioning, and it was decided to run the zero-offset VSP with only the Seismometers 1–8 (N = 8). At 1916 h, pulling out of the hole for the VSI tool string began, finishing rigdown at 0100 h on 26 July.

Transit to Site C0010

After operations were completed at Site C0009, the Chikyu moved to Site C0010 (proposed Site NT2-01J). While in transit, the drill pipe was set up and racked in preparation for running into the hole. The location was reached at 0100 h on 5 August 2009, and the ROV engaged in a seabed survey.

Hole C0010A

The Chikyu moved to the new location after completing operations in Hole C0009A, and Schlumberger engineers and technicians prepared the Schlumberger MWD and LWD tools for assembly prior to drilling Hole C0010A (target depth = 560 mbsf, water depth = 2523.7 m). The BHA included a 12¼ inch bit, RAB-8, TeleScope, stabilizer, crossover subs, 11 drilling collars, and a mechanical jar. The mud cart and jet-in tools were prepared and hung below the Chikyu in the LCA prior to drifting to the site. The ROV was again deployed for the jet-in, which occurred on 5 August at 0745 h. The jetting-in included placing a Mudmat and 20 inch casing to 41 m DSF.

The BHA was made up of a 12¼ inch bit, with an 8¼ inch LWD GVR measuring natural GR and resistivity, and the MWD-PowerPulse measuring direction and inclination, torque, and weight on bit. After MWD and LWD drilling to 402 m DSF, operations were suspended on 9 August to move the Chikyu to safety, out of the path of Typhoon "Etau," and wait on weather. Although the winds and wave predictions were not very severe (21–31 m/s winds and 5.9–9.5 m swells), the heave prediction was of greater concern. Heave had a detrimental influence on the LWD data quality, and the Co-Chief Scientists and Operations Superintendent (OSI) decided to ream and relog the hole from 2900 to 2970 m DRF, in order to improve the data quality around the fault zone target and to better define locations for screen joint placement. After the storm passed, the Chikyu returned to Site C0010 to resume drilling operations to TD, arriving on the morning of 12 August at 0200 h. Reaming operations began at 0300 h and included relogging the 2900–2970 m DRF section. TD (3107 m DRF, 555.00 m DSF) was reached on 12 August at 1715 h, when circulation and Hi-Vis mud was pumped into the hole. Operations continued with a wiper trip to the 20 inch casing shoe at 41 m DSF and then running back to the bottom of the hole. Because the wiper trip exhibited tightness in one section of the hole below 2995 m DRF even after reaming, reaming continued from 2995 to 3107 m DRF. After spotting with kill mud, pulling out of the hole to 2584 m DRF, and then washing to 2543 m DRF to clean the wellhead, pulling out of the hole continued to surface while recovering the ROV in preparation for moving the Chikyu to a LCA. At 1700 h, the BHA was back on the drill floor.

The Chikyu moved upcurrent, and then 13 nmi northwest of Site C0010 to an LCA to run the casing pipe, finishing preparations on 13 August. After examining the LWD data from Runs 1 and 2, the bottom depth of the screen casing joints was set at 2959 m DRF (407.59 m DSF). Casing was run into the water column, and the Chikyu started drifting to Hole C0010A on 14 August. At 1120 h on 15 August, the casing was run into Hole C0010A and reached 500 m DSF at ~1443 h. At 2130 h pulling out of the hole began, and at 2230 h the stinger was out of the hole. There was no signal from the cement dart to show that it had landed/seated properly, so a scraper run was planned. There was a break while the ROV umbilical was under repair, during which the 8½ inch drill collar was made up for a scraper run. The scraper run was cancelled after the cement dart was found when the BHA was disassembled. Instead, a drift in from 2 nmi above Site C0010 for a sweep entered the hole at 1210 h on 17 August and finished at 1400 h, reaching deck at 1621 h. With the sweep finished, the dummy run could begin. On 19 August, OBSs used in conjunction with VSP operations at Site C0009 were acoustically released and recovered by the supply ship, Kaiko, at 2020 h on 20 August.

Dummy run

The dummy run began in the LCA at 0830 h on 18 August and involved testing whether it could be run through the 9 inch casing, since it was discovered that the dummy run sensor carrier was warped. After confirming that it could pass though the casing unimpeded at 0900 h on 18 August, the entire array was made up beginning at 1215 h and run into the hole at 1500 h. During these operations, the smart plug was tested in preparation for installation in Hole C0010A. There was considerable vortex-induced vibration from the strong current (4.5 kt) during drifting in to location, and the carrier was held at 1650 mbsl for ROV inspection. At 1750 h on 19 August, the ROV was deployed and at 2045 h reached the carrier. Visual inspection revealed that the strainmeter and tubing below were lost, as well as one of the two seismometers. The remaining seismometer and accelerometer remained attached, and at 2130 h, after meeting with the OSI, the Co-Chief Scientists decided to recover the carrier to the surface for further inspection. As Chikyu moved north 9 nmi to the LCA, the carrier was pulled up, reaching deck at 0400 h on 20 August. The carrier showed signs of polishing and cracking and required around 4 h for the ship's welder to repair. The second dummy run carrier used only the accelerometer and a dummy strainmeter with two tubing joints below the seismometer, and it was decided to stab the reentry cone 2–3 times with no attempt to pass the carrier into the hole. The carrier was returned to the water at 1500 h on 20 August and lowered below the Kuroshio Current, and the Chikyu drifted back to Hole C0010A. At 0915 h on 21 August, the Chikyu returned to the site and jumped the ROV in preparation for stabbing the wellhead. At 0955 h the carrier was ready for stabbing into Hole C0010A, which began at 1010 h, followed by the second stab and the third at 1025 h. Pulling out of the hole began at 1040 h, and the carrier reached the drill floor at 1630 h.

Smart plug

The smart plug was made up and welded to the crossover sub at 0525 h on 22 August and then run into the hole. Drifting to Site C0010 began, and at 1350 h, 4 nmi from the site, the ROV was deployed. At 1709 h, the Chikyu was still 9.2 nmi from Hole C0010A, arriving at 0110 h on 23 August. There was another delay as the ROV umbilical needed work to fix another broken strand. The smart plug and packer were run into Hole C0010A at 0404 h, and the packer was set at 0850 h. The drill string was removed at 0930 h while the Chikyu moved again to the LCA, this time only 3 nmi from Site C0010. Upon recovery, it was discovered that the running tool had sheared off of the drill pipe in the water column at a 3½ inch tubing connection. The corrosion cap was attached to the ROV carrier, in preparation for setting in at the wellhead. At 1800 h, the ROV was launched but experienced problems with the umbilical again at 2030 h. After troubleshooting was completed, the corrosion cap was finally set at 1015 h on 24 August. The ROV began recovery of the transponders but again ran into trouble and was recovered on deck. It was decided to recover the remaining three transponders with the Kaiko, after acoustically releasing them from the seafloor. By 1200 h on 25 August, with all transponders recovered, the Chikyu began moving toward Site C0011 (proposed Site NT1-07).

Transit to Site C0011

After operations were completed at Site C0010, the Chikyu moved to Site C0011 (proposed Site NT1-07). While recovering the transponders at Site C0010, the drill pipe was set up and racked in preparation for running into the hole. The location was reached at 1700 h on 25 August 2009.

Hole C0011A

The Chikyu moved to the new location after completing operations in Hole C0010A, and Schlumberger engineers and technicians prepared the Schlumberger MWD and LWD tools for assembly, prior to drilling Hole C0011A (target depth = as deep as possible or 900 mbsf, water depth = 4049 m). Because the water depth was too great for ROV placement of transponders and the ROV was under repair, the six transponders were dropped from the surface. All transponders were dropped by 0400 h on 26 August. At 0845 h on 26 August, the 12¼ inch bit LWD/MWD BHA was run into the hole, and a calibration check was conducted between the Big Head transducers on the ship and the transponders deployed on the bottom. At 1900 h on 26 August, a prespud meeting was held to determine target depth (900 m LSF), jet-in program, and conditions for stopping drilling. Spud-in of Hole C0011A was achieved at 2239 h on 26 August, and the water depth was confirmed by MWD GR measurement at 4049 m. After jetting in to 41 m DSF, drilling the 12¼ inch hole commenced from this depth. There were short wiper trips and sweeps to ensure that the borehole condition remained good and to prevent getting the BHA stuck in the hole when the available drilling time ran out. We reached TD (952 m LSF) at 2400 h on 29 August, spotted 121 m3 of 1.30 g/cm3 kill mud, and began pulling out of the hole. The BHA reached the surface at 1300 h on 30 August, and the tools were laid down for LWD data recovery. In the meantime, the Chikyu moved to the rendezvous point for the supply ship, the Kairei, to load and backload cargo for Expedition 322.

Transit to Yokkaichi

After finishing laydown of the BHA and drill pipe and finishing cargo loading with the Kairei, the supply ship was released and the Chikyu continued moving to Ise Bay to dock at the port of Yokkaichi, Japan, reaching the headlands at 1600 h on 30 August.